Home Contact Us Site Map  
 
       
    next up previous contents
Next: 3.16.5 Build and run Up: 3.16 Gravity Plume On Previous: 3.16.3 Code configuration   Contents


3.16.4 Model parameters


Table 3.2: Model parameters used in the gravity plume experiment.
$ g$ $ 9.81$ m s$ ^{-2}$ acceleration due to gravity
$ \rho_o$ $ 999.8$ kg m$ ^{-3}$ reference density
$ \alpha $ $ 2 \times 10^{-4}$ K$ ^{-1}$ expansion coefficient
$ A_h$ $ 1 \times 10^{-2}$ m$ ^2$ s$ ^{-1}$ horizontal viscosity
$ A_v$ $ 1 \times 10^{-3}$ m$ ^2$ s$ ^{-1}$ vertical viscosity
$ \kappa_h$ 0 m$ ^2$ s$ ^{-1}$ (explicit) horizontal diffusion
$ \kappa_v$ 0 m$ ^2$ s$ ^{-1}$ (explicit) vertical diffusion
     
$ \Delta t$ $ 20$ s time step
$ \Delta z$ $ 3.3\dot{3}$ m vertical grid spacing
$ \Delta x$ $ 13.\dot{3}-39.5$ m horizontal grid spacing


The model parameters (Table 3.2) are specified in input/data and if not assume the default values defined in model/src/set_defaults.F. A linear equation of state is used, eosType='LINEAR', but only temperature is active, sBeta=0.E-4. For the given heat flux, $ Q_o$ , the buoyancy forcing is $ B_o = \frac{g \alpha Q}{\rho_o c_p} \sim 10^{-7}$  m$ ^2$ s$ ^{-3}$ . Using $ R=10^3$  m, the shelf width, then this gives a velocity scale of $ U\sim 5 \times 10^{-2}$  m s$ ^-1$ for the initial front but will accelerate by an order of magnitude over the slope. The temperature anomaly will be of order $ \Delta \theta \sim 3 \times 10^{-2}$  K. The viscosity is constant and gives a Reynolds number of $ 100$ , using $ h=20$  m for the initial front and will be an order magnitude bigger over the slope. There is no explicit diffusion but a non-linear advection scheme is used for temperature which adds enough diffusion so as to keep the model stable. The time-step is set to $ 20$  s and gives Courant number order one when the flow reaches the bottom of the slope.

next up previous contents
Next: 3.16.5 Build and run Up: 3.16 Gravity Plume On Previous: 3.16.3 Code configuration   Contents
mitgcm-support@mitgcm.org
Copyright © 2006 Massachusetts Institute of Technology Last update 2011-01-09